Function _signature_fromstr

Lib/inspect.py:2144–2288

Private helper to parse content of '__text_signature__' and return a Signature based on it.

(cls, obj, s, skip_bound_arg=True)

def _signature_fromstr(cls, obj, s, skip_bound_arg=True):
    """Private helper to parse content of '__text_signature__'
    and return a Signature based on it.
    """
    Parameter = cls._parameter_cls

    clean_signature, self_parameter = _signature_strip_non_python_syntax(s)

    program = "def foo" + clean_signature + ": pass"

    try:
        module = ast.parse(program)
    except SyntaxError:
        module = None

    if not isinstance(module, ast.Module):
        raise ValueError("{!r} builtin has invalid signature".format(obj))

    f = module.body[0]

    parameters = []
    empty = Parameter.empty

    module = None
    module_dict = {}

    module_name = getattr(obj, '__module__', None)
    if not module_name:
        objclass = getattr(obj, '__objclass__', None)
        module_name = getattr(objclass, '__module__', None)

    if module_name:
        module = sys.modules.get(module_name, None)
        if module:
            module_dict = module.__dict__
    sys_module_dict = sys.modules.copy()

    def parse_name(node):
        assert isinstance(node, ast.arg)
        if node.annotation is not None:
            raise ValueError("Annotations are not currently supported")
        return node.arg

    def wrap_value(s):
        try:
            value = eval(s, module_dict)
        except NameError:
            try:
                value = eval(s, sys_module_dict)
            except NameError:
                raise ValueError

        if isinstance(value, (str, int, float, bytes, bool, type(None))):
            return ast.Constant(value)
        raise ValueError

    class RewriteSymbolics(ast.NodeTransformer):
        def visit_Attribute(self, node):